ci: update macos-13 to macos-15 (Intel runner retired)

Author: linuxmobile

.github/workflows/ci.yml

@@ -16,7 +16,7 @@ jobs:
             target: aarch64-unknown-linux-gnu
           - os: macos-latest
             target: aarch64-apple-darwin
-          - os: macos-13
+          - os: macos-15
             target: x86_64-apple-darwin
           - os: windows-latest
             target: x86_64-pc-windows-msvc